Ho all Is it possible to change the socket of the ATMEL chip in ARDUINO UNO into a ZIP socket ?Elico

Basically no. While a 28pin slim DIP socket has the same pin spacing as the standard dip socket used on the arduino board, the Zip socket is physicall longer and wider and will interfer with other components already mounted on the board. You would have to build some kind of 'stand-off' arrangement to allow the zip socket to be mounted above the board surface. The following isn't a good picture of what I did to allow a zip socket to attach to a arduino standalone board, but it might give you a good idea of how much larger a zip socket is then a standard dip socket and why you need to be creative.

No need really - use the optiloader with the barechip in a solderless breadboard, no expensive ZIP socket needed.

https://github.com/WestfW/OptiLoader

// If the aim is to reprogram the bootloader in one Arduino using another// Arudino as the programmer, you can just use jumpers between the connectors// on the Arduino board. In this case, connect:// Pin 13 to Pin 13// Pin 12 to Pin 12// Pin 11 to Pin 11// Pin 10 (of "programmer") to RESET (of "target" (on the "power" connector))// +5V to +5V and GND to GND. Only the "programmer" board should be powered// by USB or external power.